JPH051674A - Driven gear for rotating gear pump - Google Patents

Abstract

(57) [Summary] [Purpose] By adding components that do not impair the weight reduction, a large pressure receiving area is secured during powder molding to increase the strength of the green compact and the rigidity of the upper and lower punches. In addition, a driven gear for a rotary gear pump that can be manufactured at low cost is provided. [Structure] An inner tooth 2 is formed on an inner peripheral portion of a ring-shaped gear body 1, and an outer peripheral portion of the gear body 1 is formed in an uneven shape corresponding to the inner tooth 2, and an outer peripheral portion of the gear body 1 is formed. The ribs 5 that connect the adjacent peak portions 4 are formed in each of the valley portions 3 in FIG.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driven gear used in a rotary gear pump such as a trochoid pump.

[0002]

2. Description of the Related Art Generally, in a rotary gear pump (for example, a trochoidal pump), a driven gear is rotatably fitted inside a pump case, a drive gear is arranged inside the driven gear, and a waveform (trochoidal tooth profile) of the drive gear is formed. The formed external teeth are intermeshed on one side and inscribed on the other side by the internal teeth of the driven gear, which has one more tooth and which is formed in a waveform (trochoidal tooth profile). The driven gear is rotated by, and the fluid such as fuel is sucked from the suction port and discharged from the discharge port by utilizing the volume change of the closed space portion partitioned by the teeth inscribed between both gears.

In such rotary gear pumps, the drive gear and the driven gear are often made of the same type of iron-based material, and therefore there is a disadvantage that the power loss during operation is large and the generated noise is large.

Therefore, conventionally, these problems have been solved as problems of tooth shapes and tooth profile errors of the driven gear and the drive gear, but it is not sufficient and cannot be a fundamental solution, and it is disclosed in JP-A-60-128983. As disclosed in the publication, it has been proposed to solve the problem of weight of the tribun gear.

In the tribun gear based on this idea, the outer peripheral portion of the gear which has been formed in a circular shape up to now is not the uneven portion corresponding to the inner teeth 2 as shown in FIG. The whole gear is lightened to reduce the weight of the entire gear.

[0006]

However, when the driven gear 6'is manufactured by powder molding, the pressure receiving area is smaller than when the outer peripheral portion of the gear has a circular shape, so that the strength of the green compact becomes weaker. Also, the rigidity of the upper and lower punches is reduced. If the strength of the green compact is weak,
There is a possibility that the green compact may be cracked or damaged, or the product may not have a predetermined strength. Further, since the outer peripheral portion of the gear is formed in an uneven shape instead of a circular shape, and the shape of the peak-equivalent portion in the outer peripheral portion is different from the peak shape of the internal teeth, the mold used is complicated and expensive. .

Therefore, the present invention has been made to solve the above-mentioned problems, and is large in powder molding as in the case where the outer peripheral portion of the gear has a circular shape by the addition of a simple structural portion which does not impair the weight reduction. An object of the present invention is to provide a driven gear for a rotary gear pump, which secures a pressure receiving area, increases the strength of the green compact, has high rigidity of the upper and lower punches, and can be manufactured at low cost.

[0008]

According to the driven gear for a rotary gear pump of the present invention, inner teeth are formed on the inner peripheral portion of a ring-shaped gear body, and the outer peripheral portion of the gear body is made uneven to correspond to the inner teeth. At the same time as forming the ribs, ribs that connect the adjacent peaks are formed in each valley in the outer peripheral portion of the gear body.

[0009]

[Function] Since the outer peripheral portion of the gear has a structure in which the rib portion is left without removing the entire portion except the uneven portion (outer peripheral excess portion) corresponding to the internal teeth, when manufacturing by powder molding As in the case where the outer circumference of the gear is circular, a large pressure receiving area is secured, the strength of the green compact is increased, the upper and lower punches have high rigidity, and they can be manufactured at low cost. You can use one.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a front view showing the entire driven gear, and FIG. 2 is a sectional view taken along the line AA of FIG.

In the figure, reference numeral 1 is a gear main body, and inner teeth 2 are formed on the inner peripheral portion thereof.

An outer peripheral portion of the gear body 1 is formed in an uneven shape corresponding to the inner teeth 2, and ribs 5 connecting adjacent crests 4 at the center of wall thickness are formed in each valley 3 of the outer peripheral portion. Are formed.

3, 4, 5, 6, and 7, the powder molding apparatus for forming the driven gear 6 as described above is used in each step (two steps of filling raw material powder, compression molding, and taking out a molded product,
(Supply of raw material powder).

Reference numeral 7 is a die, 8 is a fixed lower punch, and 9 is a core. The die 7 is fitted to the outside of the fixed lower punch 8, and the core 9 is fitted to the central portion of the fixed lower punch 8. Then, the die 7 and the core 9 are integrally supported on the fixed punch 8 via an actuator so as to be able to move up and down.

Reference numeral 10 denotes a product take-out device provided with a pair of right and left gripping pieces 11, which are arranged at a predetermined position on the die 7 so that the gripping pieces 11 are directly above and concentric with the fixed lower punch 8. And, the gripping pieces 10 can be separated from each other or can approach each other,
Moreover, it can be moved to a predetermined position outside the mold.

An upper punch 12 is arranged above the gripping piece 11 and at a position concentric with the fixed lower punch 8, and is supported by an actuator so as to be able to move up and down.

A core escape hole 13 is provided at the center of the upper punch 12.

Reference numeral 14 denotes a cavity, which is formed by the die 7, the lower fixed punch 8, the core 9, and the upper punch 12 which is passed through the gripping pieces 10 and descends to be fitted into the die 7.

First molding portions 15a and 15b for molding the gear body 1 and the internal teeth 2 together with the die 7 and the core 9 are provided on the upper portion of the fixed lower punch 8 and the lower portion of the upper punch 12, respectively.
And a second molding part 1 for molding the rib 5 together with the die 7.
6a and 16b are connected in series.

Next, description will be given of a case where the powder compact W as the base of the driven gear 6 is compacted by using the powder compacting apparatus constructed as described above.

As shown in FIG. 3, when the core 9 is raised together with the die 7 with respect to the lower fixed punch 8, the upper portion of the lower fixed punch 8 serves as the bottom portion of the raw material powder A in the die 7.
To fill.

As shown in FIG. 4, the product take-out device 10
The upper punch 12 is passed through between the gripping pieces 11 and the core 9 is fitted into the escape hole 13 of the upper punch 12, and the upper punch 12 is fitted into the die 7 to form the fixed lower punch 8 and the upper punch 12. The raw material powder A in the cavity 14 is compressed in between. Thereby, the green compact W is molded.

As shown in FIG. 5, the upper punch 12 is raised to its original position, and then the die 7 is lowered together with the core 9 to remove the maximum outer diameter portion of the green compact W from inside the die 7 and press the die. After removing the core 9 from the powder W, the product take-out device 10
The gripping piece 11 is placed at the maximum outer diameter portion with the green compact.

As shown in FIG. 6, after the gripping piece 11 of the product take-out device is closed and the green compact W is gripped, the core 7 and the die 7 are raised to the original position. As a result, the green compact W is taken out of the mold.

As shown in FIG. 7, the product take-out device 10
While the green compact W is discharged by the above, the raw material powder A is supplied into the die 7 with the upper part of the lower fixed punch 8 as the bottom part, and the above steps are repeated.

[0027]

As described above, according to the present invention, internal teeth are formed on the inner peripheral portion of the ring-shaped gear body, and the outer peripheral portion of the gear main body is formed to have irregularities corresponding to the inner teeth. Ribs that connect adjacent crests are formed in each trough on the outer periphery of the gear body, so to speak, while removing the outer periphery of the gear, except for the irregularities corresponding to the internal teeth (outer peripheral surplus). It has a structure in which the rib portion is left without removing all meat. For this reason, in the case of manufacturing by powder molding, a large pressure receiving area is secured as in the case where the gear outer peripheral portion is circular, so that the strength of the green compact can be increased, the upper and lower punches have high rigidity, and the cost is low. The conventional die and core can be used. Therefore, the driven gear can be surely reduced in weight, and can be manufactured easily, reliably and inexpensively.

[Brief description of drawings]

FIG. 1 is a front view showing an entire driven gear according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view showing the powder molding apparatus in a state of being filled with raw material powder.

FIG. 4 is a cross-sectional view showing the same device in a state during compression molding.

FIG. 5 is a cross-sectional view showing the same device in a state where the green compact is taken out from the die.

FIG. 6 is a cross-sectional view showing the same device in a state where a green compact is taken out from a lower fixed punch.

FIG. 7 is a cross-sectional view showing the same apparatus in a state of carrying out a green compact and supplying a raw material powder.

FIG. 8 is a front view showing a conventional driven gear.

[Explanation of symbols]

 1 Gear body 2 Internal tooth 3 Valley 4 Crest 5 Rib 6 Driven gear

Claims (1)

Claim: What is claimed is: 1. A ring-shaped gear body has inner teeth formed on an inner periphery thereof, and an outer periphery of the gear body is formed to be uneven corresponding to the inner teeth. A driven gear for a rotary gear pump, characterized in that a rib connecting between adjacent peaks is formed in each valley in the outer peripheral portion of the driven gear.